The candidate, Hirofumi Tanaka, Ph.D. is a physiologist currently supported by an individual NRSA from NIA. His immediate goal of this award is to acquire the new experimental skills (e.g., ultrasonography- based measurements of arterial compliance) and overall research experiences that will be used to answer important physiological questions in gerontology/geriatric medicine. His long-term goals are to pursue a career as an independent investigator in the area of aging, physical activity, and cardiovascular function as it pertains to human health and disease, and to develop and direct an independent, extramurally-supported research laboratory. The proposed K01 award would provide him with the opportunity to achieve these goals. The environment for Dr. Tanaka is outstanding. The sponsor, Douglas R. Seals, Ph.D is an established investigator and mentor in aging research, and has a well-funded laboratory. Structured activities, including formal course work, participation in journal clubs and seminar series, regular mentoring interactions, and participation in scientific meetings have been incorporated in his training plan. An advisory committee composed of experienced senior investigators will provide mentoring in the various technical aspects associated with the training plan. Thus, the sponsor, his department, and consulting mentors collectively provide an outstanding research environment, resources, and administrative support that will facilitate the candidate's development into an independent investigator in cardiovascular aging research. The general aim of the research project is to determine; 1) if the age- related decrease in dynamic arterial compliance and its autonomic nervous system (ANS) and cardiovascular consequences observed in sedentary adult humans, also occur in habitually physically active humans; and 2) whether a program of regular aerobic exercise can eliminate or partially reverse the decline in arterial compliance and its ANS-cardiovascular sequelae in previously sedentary middle-aged and older humans. The general hypothesis is that in contrast to sedentary adults, dynamic arterial compliance does not decline with advancing age in habitually exercising humans, and that regular aerobic exercise will improve arterial compliance and its ANS-cardiovascular sequelae in previously sedentary middle-aged and older adults. The expected results wold provide a scientific basis for the use of regular aerobic exercise as a therapeutic strategy for both primary and secondary prevention of the age-related reduction in arterial compliance and its associated adverse cardiovascular effects.